A semiconductor memory device is a memory device embodied by using a semiconductor, such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), or indium phosphide (InP). Semiconductor memory devices are broadly categorized into volatile memory devices and nonvolatile memory devices.
A volatile memory device is a memory device that loses stored data when power supply is cut off. Volatile memory devices include a static random access memory (SRAM), a dynamic RAM (DRAM), and a synchronous DRAM (SDRAM). A nonvolatile memory device is a memory device that retains stored data even if power supply is cut off. Nonvolatile memory devices include a read-only memory (ROM), a programmable ROM (PROM), an electrically programmable ROM (EPROM), an electrically erasable and programmable ROM (EEPROM), a flash memory device, a phase-change RAM (PRAM), a magnetic RAM (MRAM), a resistive RAM (RRAM), and a ferroelectric RAM (FRAM). Flash memory devices are broadly divided into a NOR type and a NAND type.
In recent years, research has been conducted on a semiconductor memory device having a 3-dimensional array structure to improve the integration density of semiconductor memory devices. In the semiconductor memory device having the 3-dimensional array structure, it is possible that Y-disturbance occurs in an unselected string, unlike a semiconductor memory device having a 2-dimensional array structure.